Process of making permanent metal molds from a permanent master positive mold



wee. 9, 1924- 1,518,271

P. w. MULDER PROCESS OF MAKING PERMANENT METAL MOLDS FROM A PERMANENT MASTER POSITIVE MOLD Filed March 6, 1922 FIG-I l N Vii! TOR.

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Patented Dec. 9, T924.

aura s arrnr OFFICE.

PETER W. MULDER, F LAY CITY, MICHIGAN, ASSIGNOR 1'0 GEORGE M. HOLLEY,

- 0F DETROIT, MICHIGAN.

PROCESS OF MAKING PERMANENT-METAL ldIOLDS FROM A PERMANENT MASTER PUSITIV'E OLD.

Application flied march 8, 1922. Serial No. 5 1L288.

To all whom it may concern:

Be it known that T, ALBERT A. MARTELIJ, a citizen of the United States, residing at lmlay City, in the county of Lapeer and a State of Michigan, have invented certain new and useful Improvement in Processes of Making Permanent Metal Molds from a Permanent Master Positive Mold, of which the following is a specification.

The object of this invention is to reduce the cost of making permanent metal molds; secondly to produce hollow permanent metal molds having a substantially uniform wall thickness; thirdly to produce permanent w molds having a smooth surface which accurately reproduce the contour of a permanent master positive mold; and lastly to make such molds of cast iron from a cast iron master positive mold.

The means for carryin out this invention is illustrated in the rawings. Pigure 1 shows a cross section through the mold.

-Pigure 2 shows a plan view of the ermanent mold cast in the mold shown in Flgure 1.

In Figure 1, A is the cast iron master positive mold supported on a baked dry sand core backing B; G is a screw locking the mold A to the backing B; D is a dry sand core which forms with the backing B the hollow negative mold or matrix E; F is the gate through which the molten metal is poured into the space E between the core 1) and the backing B; G is one of the risers which permit the escape of the gases in a well known manner.

The core backing B andthe core D are both made of core sand baked in core driers in the ordinary way.

The method of carrying out this invention is as follows: The permanent cast iron positive mold A is made of iron having the same chemical analysis as the analysis of the-metal to be poured thereon, the shrinkage of the positlve master mold and the negative mold cast thereon being therefore the same. The mold A is filed and polished and is then coated with a coating of" metallic oxide applied by a blow torch, preferably an. oxy-acetylene flame. The actual method practiced by the applicant bein to raise the temperatureof the oxy-acety one blow torch so as to give a pure white flame and insert in a chamber the metal whose oxide is to be deposited on the surface of the master metal mold. This metal is burnt within the flame, which is an oxidizing flame, and the particles of oxide are carried The temperature of the permanent master at mold is raised slightly by means of a blow torch so as to prevent any possibility of moisture adhering to the surface of the mold. Then the cast iron master mold A is coated with lamp black by means of a smoky flame. The core D is then placed over the dry sand core backing B and located by means oit' dowel ins, not shown. The sur faces of both and l) are dusted with graphite in the well known 'manner.

The core and core backing, together with the master mold A, are then placed in a flask. The cast iron is then poured in at P, preferably at a temperature in excess of 2500 F. As the metal flows in at F, through the matrix E, it flows over the master permanent mold A and raises the temperature of this mold and the iron whlch ultimately comes to rest opposite the permanent master mold A is therefore not chilled by the permanent master mold A. In addition, the coating of lamp black, together with the under coating of metallic oxide, contribute to the lack of chilling, which practically eliminates the distortion in the permanent cast iron mold A.

When the casting E is set in the matrix, but whilst it is still red hot, that is to say within 3 minutes, the flask is opened, the casting E is inverted, the core D is broken and the permanent master positive mold A is removed from the casting E by means of the screw C. The advantage gained by this method is that the metal flows through}? and E over the positive master mold K, 100 without being chi ed thereby, and without picking up particles ofsand, as would be the case of green sand were used in making B and D. Y

f the'mold A were mounted on a metal back in place of bein mounted in the dry sand core backing a chilled casting would result and in addition to the distordom from rats that is obtained by the applicants method would not be obtained. The number of bolts C used to retain the permanent master A in place, depends on the shape and size of A.

Another advantage of using dry core sand is that such a mold is porous and therefore the cast iron is automatically vented whilst it is cast and whilst it is setting. These permanent metal molds produce a satisfactory die at a much lower cost than the machine cut dies which they replace.

The best results with this process have been obtained by using a coating of tin oxide (stannic oxide) on the permanent cast iron master mold A, as I am thereby enabled to pour the iron at a very high temperature (over 2500 F.).

The applicant has found that when he pours a quantity of iron over his mold, as indicated in the drawings, that the permanent positive master A is raised to substantially the same temperature as that of the molten metal itself, so that on breaking the core the color of A is substantially the same color as that of the mold E. It follows, therefore, that assuming that the metal cast is substantially ofthe same composition as that of the master positive mold itself that there need be no correction for expansion as obviously the dimensions of the mold will exactly correspond with the dimensions of the permanent positive. master mold. While the elimination of the correction for contraction is not the main object of this invention it is an advantage which the applicant has found of great convenience in the manufacture of these molds.

In Figure 2 the permanent mold is shown in elevation, the gate H having a contracted throat J and the mold being provided with a vent or riser K.

These molds are to be used in the vertical position so that on opening or separating the two halves the castings are easily released and discharged.

By making the molds hollow the cooling.

of the permanent mold is facilitated and the distortion is limited so as to be practically eliminated.

What I claim as my invention is:

1. The method of manufacturing permanent metal molds, which consists in employin a metallic master mold having a suitab y fashioned surface, and flowing a'quantity of'molten metal over the surface of said master mold prior to the solidification of any metal in contact with said surface.

2. The method of manufacturing permanent metal molds from a positive metal master mold, which consists in locating said positive metal master mold in co-operative relation to a complementary sand mold, and in flowing molten metal over said metal master mold to raise the temperature thereof prior to the solidification of metal in contact therewith.

3. The method of manufacturing permanent metal molds from positive metal master molds which consists in coating the surface of the metal master mold with a refractory metallic oxide, in locating said master mold in co-operative relation to a complementary sand mold, and in pouring the molten metal in the combined molds. 4. The method of manufacturing permanent metal molds from positive metal mas ter molds, which consists in coating the surface of said metal master mold with a refractory coating, in co-operative relation to locating said master mold in a complementary sand mold, and in flowing molten metal over said metal master mold to raise the temperature thereof prior to the solidification of metal in contact therewith.

5. The method of manufacturing permanent metal molds from a positive metal master mold, which consists in coating the surface of said master mold with a refractory lining, locating said master mold in cooperative relation to a complementary sand mold, coating the refractory coated surface with a carbon deposit, and in flowing the molten metal within said sand mold over said master mold to raise the temperature thereof prior to the solidification of metal thereagainst.

6. The method of manufacturing permanent cast iron metal molds from positive metal master molds, which consists in coatingthe surface of the master mold with a refractory lining, locating said master mold within a complementary sand mold, fiowing the molten cast iron through said sand mold over the surface of said master mold to raise the temperature thereof prior to solidification of metal thereagainst, and in removing the master mold from the casting while the latter is still at a high temperature.

7. The method of manufacturing cast iron molds from a positive master mold of cast iron having the same chemical composition as the cast iron mold, which consists in looking the positive master mold to a dry sand backing, superimposing a dry sand core and pouring molten cast iron between the core and the backing and over the positive master mold so as to produce a metal mold for the purpose described.

8. The method of manufacturing cast iron metal molds from a positive master mold of cast iron having substantially the same chemical composition as the cast iron mold, which consists in looking a positive master mold to a dry sand backing, superimposing a dry sand core and pouring molten cast iron between the core and the backing and over the positive master mold so as to produce a hollow metal mold, for the purpose described.

9. The method of manufacturing cast iron composition as the cast iron mold, whichconsists in locating a positive metal master mold on a dry sand-backing, superimposing a dry sand core and pouring molten cast iron between the core andthe backing and over the positive master mold so as to produce a metal mold for the purpose described 10. The method of manufacturing cast iron permanent metal molds from a cast iron positive master mold which consists in locating a positive master mold on a dry sand backing, superimposing a dry sand core and pouring molten metal between the core and the backing; allowing the casting thus formed to set, breaking the dry sand backing and removing the positive master mold from the cast iron mold whilst the newly cast cast iron mold is still red hot.

11. The method of manufacturing permapouring molten metal onto the metal positive 30 mold thus protected.

12. The method of manufacturing permanent metal molds which consists in employing a metallic master mold, coating the surface of said metallic master mold with a re- 35 fractory lining and pouring molten metal over the surface of said master mold.

13. The method of manufacturing a hollow metal box-like structure having a depression on one face thereof which serves as 43 a mold, which consists in employing a me tallic master mold having a suitably fashioned refractory surface, and flowing a quantity of molten metal first into the mold surrounding the metallic master mold before 4:-

the molten metal strikes the fashioned surface of the master mold.

In testimony whereof I aflix my signature.

PETER W. MULDER. 

